JP2020112740A - Virtual image display device - Google Patents

Abstract

To provide a virtual image display device that can be maintained in a more compact shape that fits into the head shape of an observer in widening an angle of view of an HMD.SOLUTION: A virtual image display device comprises an image element for displaying an image and a light guide member for guiding image light from the image element through reflection and transmission at a plurality of light guide surfaces. With regard to an incident side light guide surface and an emissive side light guide surface adjacent to each other, and an opposing light guide surface opposed to the incident side light guide surface and the emissive side light guide surface among a plurality of light guide surfaces, the thickness between the incident side light guide surface and the opposing light guide surface is set to be smaller than the thickness between the emissive side light guide surface and the opposing light guide surface.SELECTED DRAWING: Figure 2

Description

The present invention relates to a virtual image display device represented by a head mounted display.

As a virtual image display device such as a head mounted display, as shown in, for example, Patent Document 1, in a light guide member for guiding image light in front of an observer's eye, a flat surface close to the eye and a free-form surface connected thereto are provided. It is known that they are connected with almost no step. In the following, the head mounted display is also referred to as HMD.

JP, 2017-111363, A

However, for example, when an attempt is made to further widen the angle of view with the configuration illustrated in Patent Document 1, in the light guide member, the surface that reflects the image light is made wider, and the entire light guide member is The size may also increase. There is a demand for avoiding such a situation, that is, a demand for maintaining the entire product in a more compact shape that fits the head shape of the observer (wearer) when the angle of view of the HMD is widened.

A virtual image display device according to one aspect of the present invention includes a video element that displays an image and a light guide member that guides image light from the video element by reflection and transmission on a plurality of light guide surfaces. Among the light surfaces, with respect to the adjacent light guide surface on the incident side and light exit surface on the exit side, and the light guide surface opposed to the light guide surface on the incident side and the light guide surface on the exit side, the light guide surface on the incident side is opposed to the light guide surface on the opposite side. The thickness to the surface is smaller than the thickness from the exit side light guide surface to the opposing light guide surface.

It is a perspective view explaining an appearance of an example of a virtual image display device concerning an embodiment. FIG. 3 is a plan sectional view showing an optical system and an optical path of image light in the virtual image display device. It is a conceptual plan sectional view for considering the configuration of the light guide device in the virtual image display device. It is a conceptual diagram for comparing about the structure of a light guide device. It is a graph which shows the relationship between the ratio of thickness and the light guide part length. It is a conceptual diagram for considering the structure of a light guide device from the viewpoint of the optical path of ambient light. It is a conceptual diagram which extracted a part of FIG. It is a conceptual diagram which extracted another part of FIG. 3 is a plan sectional view showing the virtual image display device of Example 1. FIG. 5 is a graph showing a relationship between a thickness ratio and a light guide length regarding Example 1. 9 is a graph showing a relationship between a thickness ratio and a light guide length regarding Example 2. 9 is a graph showing a relationship between a thickness ratio and a light guide length regarding Example 3.

Hereinafter, a virtual image display device according to an embodiment of the present invention will be described in detail with reference to FIG. 1 and the like.

As shown in FIG. 1 and the like, the virtual image display device 100 according to the present embodiment is a head mounted display (HMD) having an appearance like glasses, and for an observer or a user wearing the virtual image display device 100. The image light (image light) by the virtual image can be visually recognized, and the observer can visually see or observe the outside world image. That is, the image light and the external light can be visually recognized at the same time. The virtual image display device 100 includes a first display device 100A, a second display device 100B, and a frame unit 102.

The first display device 100A and the second display device 100B are portions that form a virtual image for the left eye and a virtual image for the right eye, respectively, and first and second optical members 101a and 101b that cover the viewer's eye in a see-through manner. , And first and second image forming main body portions 105a and 105b, respectively. The first and second image forming main body portions 105a and 105b will be described later, but each is composed of an optical system for image formation such as a display device (video element) and a projection lens, a member that accommodates these optical systems, and the like. Has been done. Note that the display device (video element), the projection lens, and the like are supported and housed by being covered with a cover-shaped exterior member (case member) 105d. The first and second optical members 101a and 101b guide the image light formed by the first and second image forming main bodies 105a and 105b, and at the same time, allow the external light and the image light to overlap and be visually recognized. And constitutes a light guide device including the light guide member. Hereinafter, the first optical member 101a or the second optical member 101b is also referred to as the light guide device 20. It should be noted that the first display device 100A and the second display device 100B independently function as a virtual image display device.

The frame portion 102 is an elongated member that is bent in a U shape in a plan view, and has a thick structure that is provided by being connected to both the first optical member 101a and the second optical member 101b, that is, the pair of light guide devices 20. It has a central portion 102a and a support body 102b extending from the central portion 102a along the first and second optical members 101a and 101b, and further forming a U-shaped bent portion.

A temple 104, which is a hanging portion extending rearward from both left and right ends of the frame portion 102, is provided, and the temple 104 can be used as a member that comes into contact with and supports an ear or temple of an observer.

Hereinafter, an example of a structure for guiding the image light GL in the virtual image display device 100 will be conceptually described with reference to the plan sectional view of FIG. 2. FIG. 2 is a diagram showing a part of the first display device 100A, and in particular, an optical system part is extracted. Although the devices for guiding the image light GL are the first display device 100A and the second display device 100B (see FIG. 1) as described above, the first display device 100A and the second display device Since the device 100B has a bilaterally symmetrical and equivalent structure, only the first display device 100A will be described, and the description of the second display device 100B will be omitted.

As shown in FIG. 2, the first display device 100A includes an image display device 80 that forms the image light GL, and a projection optical system 30 including a projection lens LS for image formation housed in a lens barrel (not shown). The image display device 80 and the light guide device 20 that guides the image light GL that has passed through the projection lens LS. The light guide device 20 includes a light guide member 10 for light guiding and see-through, and a light transmitting member 50 for see-through. Here, for example, it is assumed that the first display device 100A displays an image with a wide angle of view of 25° or more in the horizontal angle of view.

The image display device 80 can be, for example, a video element (video display element) including a self-luminous element such as an organic EL. Further, the image display device 80 includes, for example, a video display element that is a transmissive spatial light modulator, a lighting device that is a backlight that emits illumination light to the video display element, and a drive control unit that controls the operation. May be The image display device 80 has a rectangular shape, forms a rectangular image plane IP, and emits the image light GL from each position of the image plane IP. Here, it is assumed that the normal line direction of the image plane IP coincides with the optical axis direction in which the optical axis AX of the projection lens LS forming the projection optical system 30 extends.

Further, as shown in the figure, of the image light GL emitted from the image plane IP of the image display device 80, the component of the principal ray of the component light GLc emitted from the center CC of the image plane IP is the component PRc, and the periphery thereof is The component of the principal ray of the component light GLp emitted from the portion PP is referred to as the component PRp. As shown, at the eye position EY, the component light GLc from the center side is incident from the front direction without an angle, whereas the component light GLp from the peripheral side is incident at a large angle. That is, in order to widen the angle of view of the image light GL, it is necessary to consider the component light GLp from the peripheral side. In the present embodiment, the optical path of the component PRp of the chief ray of the component light GLp will be described below as a representative of the component light GLp.

The projection optical system 30 has, as a constituent element, a projection lens LS including, for example, a plurality of optical elements arranged along the direction in which the incident side optical axis AX extends, and the projection lens LS is a lens barrel (not shown). It is stored and supported by such an optical component holding member. In the illustrated example, the projection lens LS is composed of four lenses LS1 to LS4. The lenses LS1 to LS4 include, for example, those configured by an aspherical lens including both an axisymmetric aspherical surface (axisymmetric aspherical surface) and an axisymmetric aspherical surface (axisymmetric aspherical surface). ing. That is, the projection lens LS constitutes an asymmetrical optical system. Thereby, an intermediate image corresponding to a display image can be formed inside the light guide member 10 in cooperation with a part of the light guide member 10 that constitutes the light guide device 20. The projection lens LS projects the image light GL formed by the image display device 80 toward the light guide device 20 and makes it enter. Although a detailed description is omitted, the lens barrel that houses the projection lens LS is housed and supported by the exterior member 105d in FIG.

As described above, the light guide device 20 is composed of the light guide member 10 for light guiding and see-through, and the light transmitting member 50 for see-through. Further, the light guide device 20 has the main body member covered and protected by the hard coat layer being a protective layer provided on the surface portion. The light transmitting member 50 is a member (auxiliary optical block) that assists the see-through function of the light guide member 10, that is, a light transmitting portion, and is integrally fixed to the light guide member 10 to form one light guide device 20. .. The light guide device 20 is accurately positioned and fixed to the projection lens LS by being screwed to an optical component holding member such as a lens barrel.

The light guide member 10 has first to fifth surfaces S11 to S15 as side surfaces having an optical function. Of these, the first surface S11 and the fourth surface S14 are adjacent to each other, and the third surface S13 and the fifth surface S15 are adjacent to each other. Further, the second surface S12 is arranged between the first surface S11 and the third surface S13. A half mirror layer is additionally provided on the surface of the second surface S12. The half mirror layer is a light-transmitting reflective film (semi-transmissive reflective film), and is formed by depositing a metal reflective film or a dielectric multilayer film, and the reflectance for image light is appropriately set. That is, the light guide member 10 has a transmissive reflection surface that covers the front of the eye when the observer wears it. Further, among the first to fifth surfaces S11 to S15, the third surface S13 and the first surface S11 are flat surfaces. That is, these are formed on the flat surface portion of the light guide member 10. On the other hand, the second surface S12, the fourth surface S14, and the fifth surface S15 are free-form surfaces. That is, these are formed on the free-form surface of the light guide member 10.

Further, in the above case, the light guide member 10 is formed with a plurality of light guide surfaces for guiding the image light GL by the first to fifth surfaces S11 to S15, that is, with the plurality of light guide surfaces. It can be understood that the image light from the image display device 80 passing through the projection optical system 30 is guided by the reflection and transmission of the light.

Further, in this case, among the first to fifth surfaces S11 to S15 that are the plurality of light guide surfaces, the adjacent fourth surface S14 and first surface S11 are relatively closer to the image display device 80, that is, The fourth surface S14 located on the upstream side of the optical path is regarded as the incident side light guide surface IG located on the side on which the image light is incident, and is located on the side relatively close to the eye position EY of the observer, that is, on the downstream side of the optical path. The first surface S11 to be turned on can also be regarded as the exit side light guide surface OG located on the side where the image light is exited.

Further, among the first to fifth surfaces S11 to S15, which are a plurality of light guide surfaces, the third surface S13, which is arranged so as to face the fourth surface S14 and the first surface S11, is an incident side light guide. It can be regarded as an opposed light guide surface OP that faces the surface IG and the exit side light guide surface OG.

In particular, in the present embodiment, regarding the incident side light guide surface IG, the exit side light guide surface OG, and the counter light guide surface OP as described above, the thickness from the incident side light guide surface IG to the counter light guide surface OP is It is smaller than the thickness from the side light guide surface OG to the opposite light guide surface OP.

Further, in the present embodiment, in order to form the above-described arrangement relationship, the light guide member 10 has the step portion SP between the adjacent incident-side light guide surface IG and exit-side light guide surface OG. There is. The step portion SP is a portion that continuously connects the incident-side light guide surface IG and the exit-side light guide surface OG when there is a step between the incident-side light guide surface IG and the exit-side light guide surface OG. It has a connection surface SS for connecting to the OG. In other words, in the present embodiment, since the light guide member 10 is provided with the step portion SP, the distance between the incident light guide surface IG and the exit light guide surface OG to the opposing light guide surface OP. This is a mode in which there is a difference in the thickness specified by. The step portion SP has a shape that causes a difference in thickness of, for example, 2.5 mm or more in the thickness direction of the light guide member 10, and further, if necessary, in the connection surface SS or in the vicinity of the connection surface SS. Alternatively, it may be black-painted or embossed (sanded). Further, the connection surface SS can be formed into a shape that connects the two by providing a taper angle of 3° to 10° with reference to the normal direction of the exit side light guide surface OG. By configuring the connection surface SS or the vicinity thereof as described above, it is possible to suppress generation of stray light due to unintended reflection of unnecessary components of external light and image light.

Further, when the viewpoint of the above-mentioned light guide member 10 is changed, the light guide member 10 is arranged on the opposite side of the plurality of light guide surfaces from the incident side of the external light (that is, the observer side) and is adjacent to the incident side. In the side light guide surface IG and the exit side light guide surface OG, the shape in which the exit side light guide surface OG is projected more than the entrance side light guide surface IG (the entrance side light guide surface IG is more than the exit side light guide surface OG. Also has a recessed shape).

As described above, the light transmission member 50 is integrally fixed to the light guide member 10 to form one light guide device 20, and is a member (auxiliary optical block) that assists the see-through function of the light guide member 10. .. The light transmitting member 50, which is a light transmitting portion, has a first transmitting surface S51, a second transmitting surface S52, and a third transmitting surface S53 as side surfaces having an optical function. The second transmission surface S52 is arranged between the first transmission surface S51 and the third transmission surface S53. The first transmission surface S51 is on a surface that is an extension of the first surface S11 of the light guide member 10, and the second transmission surface S52 is a curved surface that is joined and integrated with the second surface S12. The three-transmission surface S53 is on a surface that is an extension of the third surface S13 of the light guide member 10. In other words, the first surface S11 and the first transmissive surface S51 are adjacent to each other, and similarly, the third surface S13 and the third transmissive surface S53 are adjacent to each other, both of which are aligned flush with each other. It forms a smooth surface.

Hereinafter, the optical path of the image light GL will be briefly described with reference to FIG. The light guide member 10 allows the image light GL to enter from the projection lens LS and guides the image light GL toward the eyes of the observer by reflection on the first to fifth surfaces S11 to S15. Specifically, the image light GL from the projection lens LS first enters the fourth surface S14 and is reflected by the fifth surface S15, and again enters the fourth surface S14 from the inside and is totally reflected. It is incident on the surface S13 and totally reflected, and is incident on the first surface S11 and totally reflected. The image light GL totally reflected by the first surface S11 is incident on the second surface S12 and partially reflected while being partially transmitted through the half mirror layer provided on the second surface S12. Re-enters and passes through, that is, passes through the first surface S11. The image light GL that has passed through the first surface S11 is incident on the eye of the observer or its equivalent position EY as a substantially parallel light flux. That is, the observer observes the image with the image light GL as the virtual image.

Further, the light guide device 20 allows the observer to visually recognize the image light through the light guide member 10 as described above, and the cooperation of the light guide member 10 and the light transmission member 50 allows the observer to form an external image with less distortion. It is supposed to be observed. At this time, since the third surface S13 and the first surface S11 are planes that are substantially parallel to each other (diopter is substantially 0), aberrations and the like hardly occur in the external light. Similarly, the third transmitting surface S53 and the first transmitting surface S51 are planes that are substantially parallel to each other. Furthermore, since the third transmitting surface S53 and the first surface S11 are planes that are substantially parallel to each other, aberrations and the like hardly occur. As described above, the observer observes the distortion-free external image through the light transmitting member 50.

As described above, in the present embodiment, in the inside of the light guide member 10, the image light from the image display device 80, as described above, includes the first surface S11 to the fifth surface including the total reflection at least twice. Light is guided by five reflections up to S15. This makes it possible to achieve both display of image light and see-through for visually recognizing external light, and to correct aberration of the image light GL.

The above-described configuration is the same in the second display device 100B shown in FIG. This makes it possible to form images corresponding to the left and right eyes, respectively.

In the present embodiment, in the light guide device 20 that guides the image light GL as described above, by providing the step by the step portion SP as described above, the opposite light guide from the exit side light guide surface OG. The thickness h ₁ to the surface OP and the thickness h ₂ from the incident side light guide surface IG to the counter light guide surface OP are configured to be different from each other. That is, h ₁ >h ₂ is set. As a result, by downsizing the light guide member 10, it is possible to maintain a more compact shape that fits the shape of the observer's head when the angle of view of the displayed image is widened.

In the case of an HMD having a configuration in which the light guide device is extended along the left-right direction (horizontal direction), which is the direction in which the eyes are arranged, including the case as in the present embodiment, and the image light is guided from the ear side of the observer to the front of the eye It is important to adjust the size of the light guide part. This is because if it is too small, the observer's face will not fit, and if it is too large, it will lead to problems in design such as appearance, and further, difficulty in mounting. In particular, when an attempt is made to widen the angle of view, the surface of the light guide member that reflects the image light becomes wider, and the size of the light guide member and the size of the entire device tend to increase. Become.

In particular, regarding the size, the length LLc illustrated in FIG. 2, that is, the length from the entrance to the exit of the image light GL in the light guide member 10 becomes a problem. More specifically, in order to maintain an appropriate size as the light guide member 10, the distance from the reference incident position to the reference emission position of the image light GL as exemplified by the length LLc is about 54 mm or less. It is known that even if the angle of view is widened, it is desirable to suppress the length to about this value. However, in order to widen the angle of view, first of all, the light-exiting side of the light guide member 10 close to the eye should be enlarged to some extent from the viewpoints of maintaining the angle of view, eye ring, and ensuring eye relief. I have no choice. Further, from the viewpoint of see-through, there is a restriction on the shape of the reflecting surface on the light emission side. For this reason, it is considered difficult to adopt a configuration for suppressing an increase in size associated with a wider angle of view. In other words, the thickness h ₁ on the light emission side is difficult to change because the size required for widening the angle of view is determined. Therefore, in this embodiment, by providing a difference in the thickness h ₂ of the light incident side with respect to the thickness h ₁ of the light emitting side, the angle of view, the length of the light guide member 10 corresponding to the length LLc Is set to be within an appropriate range. Note that, hereinafter, the length of the light guide member 10 corresponding to the length LLc is referred to as a light guide section length, and the light guide section length is defined as appropriate.

Hereinafter, referring to the conceptual plan sectional view and the like shown in FIG. 3, by tracing the optical path of the component PRc of the principal ray of the component light GLc as the central light of the image light GL, the virtual image display device 100 Regarding the size of the light guide device 20, more specifically, the length of the light guide portion of the light guide member 10 will be considered.

Here, as a premise, in the light guide device 20 or the light guide member 10 illustrated in FIG. 3, the following approximation is made for simplification of description.

First, the first to fifth surfaces S11 to S15, which are the plurality of light guide surfaces constituting the light guide member 10, are approximated by planes. In particular, among these, the first surface S11 that is the exit side light guide surface OG and the third surface S13 that is the opposite light guide surface OP that faces the first surface S11 are planes that are parallel to each other. Furthermore, the fourth surface S14, which is the incident side light guide surface IG, and the third surface S13, which is the opposite light guide surface OP that faces the fourth surface S14, are also planes that are parallel to each other. That is, the fourth surface S14 is originally a free curved surface, that is, formed on the free curved surface portion of the light guide member 10, but is regarded as a flat surface in the example of FIG. If the above is premised, the first surface S11, the third surface S13, and the fourth surface S14 are parallel to each other. Further, regarding the second surface S12 and the fifth surface S15, the angle formed by the first surface S11 and the second surface S12 and the angle formed by the fourth surface S14 and the fifth surface S15 are equal to each other. And

Next, with respect to the image light GL, the principal ray component PRc of the component light GLc as the central light passes through the optical path equal to the incident side optical axis AX and is vertically incident on the fourth surface S14 which is a flat surface. I shall. In this case, under the conditions of the first to fifth surfaces S11 to S15, the principal ray component PRc is emitted in the vertical direction from the first surface S11 via the surfaces S11 to S15. Furthermore, in this case, the reflection angles of the principal ray component PRc with respect to the first surface S11, the third surface S13, and the fourth surface S14 are always the same. Here, this reflection angle is referred to as a reflection angle α. In this case, the angle formed by the first surface S11 and the second surface S12 is α/2. Further, at the time of emission, the optical path of the component PRc is equal to the visual axis OX of the observer, and passes through the center point CT of the eye ring, that is, the point that is the center of the observer's ideal pupil.

Here, as illustrated, the normal direction of the first surface S11, the third surface S13, and the fourth d surface S14 is the Z direction, and the in-plane directions of the first surface S11, the third surface S13, and the fourth surface S14 are the same. Of these, the horizontal direction in which the eyes are lined up is the X direction. In this case, the Z direction is a direction that defines the distance from the first surface S11 or the fourth surface S14 to the third surface S13, and this is the thickness direction of the light guide member 10. That is, as illustrated, the thickness h ₁ from the exit side light guide surface OG (first surface S11) to the opposing light guide surface OP (third surface S13) and the incident side light guide surface IG (fourth surface S14). for the thickness h ₂ of to the opposite light guide surface OP from it is defined as the distance in the Z direction.

Further, based on the above premise, the definition of the light guide portion length L of the light guide member 10 is as shown in the figure so that the reference incidence position to the reference emission position of the principal ray component PRc is used as a reference. That is, the distance in the X direction from the incident side optical axis AX to the visual axis OX is defined as the light guide length L. In the figure, the light guide length L is divided into four lengths L1 to L4 with reference to the reflection position of the principal ray component PRc. That is,
L=L1+L2+L3+L4 (1)
Has become. In addition to the above, as shown in the figure, for the component PRc of the chief ray, the distance from the reflection point of the second surface S12 to the exit point of the first surface S11 is _defined as a distance h _k, and from the incident point of the fourth surface S14. The distance to the reflection point on the fifth surface S15 is defined as the distance h _m . Here, let h _k =k×h ₁ and h _m =m×h ₂ . That is, the distances h _k and h _m are shown as a ratio with respect to the thicknesses h ₁ and h ₂ .

Note that, normally, the principal ray component PRc is located at the center or near the center of the entire ray bundle of the image light GL, and therefore the reflection point of the second surface S12 and the reflection point of the fifth surface S15 are Roughly, it is desirable to come near the center of each surface. That is, it is desirable that the numerical values k and m indicating the ratio of the positions of the respective surfaces be in the middle of 0.5 in the range of 0 to 1 or in the vicinity thereof. As a specific example, it is assumed that k=0.6 and m=0.7.

Considering the triangular ratio from the figure based on the respective values defined as described above, L1=h _k ×tan α=k×h ₁ ×tan α... (2a) for each of the four lengths L1 to L4.
L2=h ₁ ×tan α (2b)
L3=h ₂ ×tan α (2c)
_{L4 = h m × tanα = m} × h 2 × tanα ... (2d)
Becomes Therefore, by substituting the above equations (2a) to (2d) into the equation (1),
L=L1+L2+L3+L4={(1+k)h ₁ +(1+m)h ₂ }×tan α... (3)
Becomes From the right side of the above equation (3), it can be seen that the value of the light guide length L can be reduced by reducing the thickness h ₂ . Furthermore, we can see how small the order can be. It is considered that other values on the right side cannot be changed to the same value as the thickness h ₂ .

For example, regarding the thickness h ₁ on the light emission side, as described above, the value of the angle of view (FOV), the eye ring whose diameter is i or 2×i in the figure, or the eye which is indicated by D in the figure. It is determined from the relationship with the relief, and is determined according to these values that determine the configuration of the virtual image display device 100. That is, if the value of the thickness h ₂ is reduced, the eyering diameter i, the eye relief D, or the angle of view must be reduced.

Further, for example, if the value of the reflection angle α is reduced, the total reflection condition may not be satisfied. The numerical values k and m are as described above, and the smaller the value, the smaller the reflection area on each surface of the image light GL.

On the other hand, regarding the thickness h _2, it is considered that the optical effect is small when the numerical value is reduced. For example, by optimizing the position and size of the step generated due to the difference between the thickness h ₂ and the thickness h ₁ , the exit side light guide surface OG (first surface S11) and the opposite light guide surface OP (first surface). By sufficiently securing the size of the third surface S13), it is possible to secure the see-through that allows the image light and the external light to be visually recognized at the same time by passing through the exit side light guide surface OG and the counter light guide surface OP. Focusing on such a point, in the present application, by making the thickness h ₂ smaller than the thickness h ₁ , it is possible to prevent the light guide portion length L from increasing when the angle of view of an image is widened.

FIG. 4 is a conceptual diagram for comparing the configurations of the light guide device 20 or the light guide member 10, and is a diagram corresponding to FIG. 3. Assuming that in the light guide member 10 illustrated in FIG. 3, the optical path of the principal ray component PRc in the light guide member 10 when the difference between the thickness h ₂ and the thickness h ₁ is not provided is indicated by a broken line in the figure. There is. It can be seen that the length L of the light guide portion is larger than that in the case of FIG. 3 indicated by the solid line.

とできる。ここで、右辺には、厚みｈ_１が残っているが、既述のように、厚みｈ_１は、画角（ＦＯＶ）やアイリング径ｉ、アイレリーフＤによって固定的に定まり、ここでは、画角（ＦＯＶ）以外のアイリング径ｉ及びアイレリーフＤは、変更しないものとし、画角（ＦＯＶ）が決まれば、厚みｈ_１は、定まるものとする。さらに、導光部長Ｌが５４ｍｍ程度かそれ以下となっていること、ｋ＝０．６程度、ｍ＝０．７程度とすること、反射角αが屈折率ｎｄにおいて全反射条件を満たすことを踏まえ、厚みの比ｈ_２／ｈ_１が、上式（４）の右辺の値あるいは、それ以下の値となるようにすることが望ましいと考えられる。 Hereinafter, description will be made with reference to the graph of FIG. This graph shows an example of the relationship between the thickness ratio h ₂ /h ₁ and the light guide length L, and the horizontal axis represents the thickness ratio h ₂ /h ₁ (unit of each thickness: mm). ), and the vertical axis is the light guide length L (unit: mm). Each curve A1 to A3, B1 to B3, C1 to C3 shows the case where the angle of view (FOV) and the refractive index nd are different. First, if the above equation (3) is transformed,

Can be Here, the thickness h ₁ remains on the right side, but as described above, the thickness h ₁ is fixedly determined by the angle of view (FOV), the eye ring diameter i, and the eye relief D. The eyering diameter i and the eye relief D other than the angle of view (FOV) are not changed, and the thickness h ₁ is determined when the angle of view (FOV) is determined. Further, it is necessary that the light guide length L is about 54 mm or less, k is about 0.6 and m is about 0.7, and the reflection angle α satisfies the total reflection condition at the refractive index nd. Considering this, it is considered desirable to set the thickness ratio h ₂ /h ₁ to a value on the right side of the above equation (4) or a value less than that.

で定義されるものを用いることが考えられる。 As described above, with respect to the items approximately shown in FIG. 3 and the like, for example, all of the plurality of light guide surfaces forming the light guide member 10 are treated as planes, or the chief ray is perpendicular to the plane. I am making it incident. For this reason, in an actual optical system, a free-form surface is used and an incident angle is attached. However, these differences in shape and angle are considered to be an error or a correctable item for the calculation of the approximate length of the light guide section. For example, regarding the incident angle and the like, in order to take into consideration the difference for each light ray, the total reflection condition accompanying it, the inclination of the incident side optical axis AX and the visual axis OX, the eyeling diameter i, etc. Instead of the reflected angle α, for example, the angle θ ₁ is

It is possible to use the one defined in.

The respective curves A1 to A3, B1 to B3, C1 to C3 in FIG. 5 satisfy the respective conditions when k=0.6, m=0.7, and the angle θ ₁ is used instead of sin α as the above requirements. Curves of the boundary to be satisfied are shown for each angle of view (FOV) and refractive index nd. For example, in the curves A1 to A3, the refractive index nd=1. The curves of the boundaries when 50, 1.55, and 1.60 are shown, respectively. Similarly, in the case where the curves B1 to B3 have a horizontal field angle of 35° and the refractive indices nd=1.50, 1.55, and 1.60, the curves C1 to C3 have a horizontal field angle of 45°. , And refractive indices nd=1.50, 1.55, and 1.60, respectively. From the graph, for example, if the thickness ratio h ₂ /h _{1 is set} to about 0.5, that is, if the thickness h _{2 is set} to about half of the thickness h ₁ , the horizontal angle of view is set to about 45° and the wide angle of view is widened. Even in the display, it is considered that the light guide length L can be set to about 54 mm. Further, from the graph, although depending on the value of the refractive index nd, that is, depending on the material of the light guide member 10, if the horizontal angle of view is 25° or more, it is necessary to make the thickness h ₂ smaller than the thickness h _1. You can see it coming out. More specifically, for example, when the refractive index is low such as the case where the refractive index nd=1.50, and the horizontal angle of view exceeds about 32°, it is necessary to satisfy h ₂ <h _1. When the horizontal angle of view exceeds about 40°, it is necessary to satisfy h ₂ <h ₁ regardless of the refractive index.

The above considerations, a different viewpoint, as one restrictions on the thickness h _2, is of the upper limit of the thickness h _2, or the upper limit of the ratio h _{2 /} h ₁ of the thickness, and can be said.

Next, as another limitation regarding the thickness h _2, the configuration of the light guide device 20 will be considered from the viewpoint of the optical path of the component light GLp on the peripheral side of the image light GL illustrated in FIG. 2 with reference to FIG. 6 and the like. To do.

As described above, from the viewpoint that the component light GLp determines the angle of view (FOV) of the image light GL, it is an important matter to consider the optical path of the component light GLp in the light guide member 10. It will be one. For example, when the step portion SP is provided in order to reduce the thickness h ₂ , it is premised that a range where each component light of the image light GL can pass is secured in the vicinity of the step portion SP. In other words, it is necessary to have a shape or structure in which the step portion SP does not overlap the passage range of the image light GL so that the image light GL is not kicked and blocked by the step portion SP. Here, in consideration of such matters, a desirable condition is considered for the optical path of the component PRp of the principal ray of the component light GLp on behalf of the component light GLc which is the ambient light of the image light GL.

In the step portion SP, which is a portion adjacent to the incident-side light guide surface IG and the exit-side light guide surface OG, the step difference d in the thickness direction (Z direction) is defined as the difference between the thickness h ₁ and the thickness h _{2 in} the connection surface SS. Is causing. Depending on the setting of each part and the refractive index of the applied material, for example, when the angle of view (FOV) is about 28° and the thickness h ₁ is about 13 mm, the value of the step d is By setting the value to about 2.5 mm or more, the light guide length L can be set within a desired range.

FIG. 6 is a conceptual plan cross-sectional view for considering the configuration of the light guide device 20, that is, the light guide member 10 with respect to the optical path of the component PRp of the principal ray of the component light GLc that is ambient light, and corresponds to FIG. It is a figure. FIG. 7 is a diagram in which a part of FIG. 6 is extracted, and FIG. 8 is a diagram in which another part of FIG. 6 is extracted.

Here, of the components PRp to be considered, the component involved in the angle of view on the light emission side (+X side), in other words, on the nose side of the observer is the component PP1 indicated by the dashed line in the figure, and the light incidence is performed. The component related to the angle of view on the side (−X side), in other words, on the ear side of the observer is a component QQ1 shown by a broken line in the drawing. It should be noted that these components PP1 and QQ1 correspond to the chief rays of the components emitted from the most peripheral one end and the other end of the image plane IP of the image display device 80 shown in FIG.

Further, here, as illustrated, among the intersections (the plurality of intersections) of the component PP1 and the component QQ1, the intersection closest to the step portion SP that is the adjacent portion is set as the intersection CS. One guideline is to prevent the intersection CS from overlapping the step portion SP. Therefore, here, the distance from the intersection CS for the thickness direction (Z direction) to the opposite light guide surface OP (third surface S13) and the distance h _c, the distance h _c as a reference for determining the lower limit of the thickness h ₂ That is, the condition for securing the optical path of the component light GLp is that the value of the thickness h ₂ is larger than the value of the distance h _c from the intersection CS to the opposing light guide surface OP.

Hereinafter, the optical paths of the component PP1 and the component QQ1 will be examined from the position EY of the eye in the opposite direction until the intersection CS is reached. Further, here, the distance from the intersection CS in the X direction (horizontal direction) to the visual axis OX is defined as the distance L _c . Further, as shown in the drawing, the total reflection angle of the component PP1 in the light guide member 10 is an angle α ₁ (that is, a reflection angle α ₁ ), and the total reflection angle of the component QQ1 is an angle α ₂ (that is, a reflection angle α ₂ ). ..

Based on the above, the outline of the method of calculating the distance h _c by expressing the distance L _c of each of the component PP1 and the component QQ1 by each of the numerical values defined above will be described below.

First, referring to FIG. 7, consideration will be given to securing of the field angle (FOV) on the nose side, that is, the component PP1. The component PP1 extends from the center point CT of the eye ring, which is the center of the eye position EY, in the direction inclined by the angle FOV/2 toward the +X side with respect to the visual axis OX, enters from the first surface S11, and is incident on the first surface S11. It is folded back by the reflection on the surface S12, is reflected by the exit side light guide surface OG (first surface S11), is reflected by the opposed light guide surface OP (third surface S13), and reaches the intersection CS. In the figure, the distance L _c is divided into four lengths P1 to P4 with reference to the reflection position of the component PP1. That is,
L _c =−P1+P2+P3+P4 (6)
Has become. Here, the distance from the incident point of the first surface S11 to the reflection point of the second surface S12 (corresponding to the distance from the reflection point of the second surface S12 to the exit point of the first surface S11 in the order of the optical path). If the triangle ratio is taken into consideration from the figure with _P as the distance h _p , then P1=(h _p +D)×tan(FOV/2)... (7a) for each of the four lengths P1 to P4.
_{P2 = h p × tanα 1 ...} (7b)
P3=h ₁ ×tan α ₁ (7c)
P4=h _c ×tan α ₁ (7d)
Becomes Note that the distance h _p is appropriately determined by the value of the distance h _{k in} FIG. 3, the shape of the light beam bundle, and the like. In the above description, the distance h _c to be calculated is included only in the length P4, and the lengths P1 to P3 are determined by other numerical values that do not include the distance h _c . The eye relief D is the same as that described above.

Next, with reference to FIG. 8, consideration will be given to securing the field angle (FOV) on the ear side, that is, the component QQ1. The component QQ1 extends from a center point CT of the eye ring, which is the center of the eye position EY, in a direction inclined by an angle FOV/2 toward the −X side with respect to the visual axis OX, enters from the first surface S11, and enters the first surface S11. The light is reflected by the surface S12, is reflected, is reflected by the exit-side light guide surface OG (first surface S11), and reaches the intersection CS. That is, it differs from the case of the component PP1 shown in FIG. 7 and the like in that the intersection CS is reached before reaching the opposing light guide surface OP (third surface S13). In the figure, the distance L _c is divided into three lengths Q1 to Q3 with reference to the reflection position of the component QQ1. That is,
L _c =Q1+Q2+Q3 (8)
Has become. Here, the distance from the incident point of the first surface S11 to the reflection point of the second surface S12 (corresponding to the distance from the reflection point of the second surface S12 to the exit point of the first surface S11 in the order of the optical path). Is taken as the distance h _Q , and considering the triangular ratio from the figure, for each of the three lengths Q1 to Q3, Q1=(h _Q +D)×tan(FOV/2)... (9a)
Q2=h _Q ×tan α ₂ (9b)
Q3=(h ₁ −h _c )×tan α ₂ (9c)
Becomes The distance h _Q is appropriately determined by the value of the distance h _{k in} FIG. 3, the shape of the ray bundle, and the like. In the above description, the distance h _c to be calculated is included only in the length Q3, and the lengths Q1 and Q2 are determined by other numerical values that do not include the distance h _c .

From the above, regarding the distance L _c , first, from the above equations (6) and (8),
L _c =−P1+P2+P3+P4=Q1+Q2+Q3 (10)
Is. From this, the above expressions (7a) to (7d) and (9a) to (9c) are further substituted in the middle side and the right side of the above expression (10), and the distance h _c is set to the length P4, Q3. If the distance h _c between the middle side and the right side is arranged in consideration of the fact that the distance h _c is included in only the condition, the condition that the distance h _c should satisfy can be obtained.

In the present embodiment, the thickness h ₂ is as follows for the distance h _c determined as described above.
h ₂ ≧h _c (11)
It is a desirable condition that the intersection CS does not overlap the step SP. Furthermore, referring to the thickness ratio h ₂ /h ₁ ,
h ₂ /h ₁ ≧h _c /h ₁ (12)
That is, it is desirable. Considering the angle of view (FOV), the eye relief D, and the eyeling diameter i on the right side of the above equation (12),
For the thickness ratio h ₂ /h ₁ ,
h ₂ /h ₁ ≧0.5 (13)
It is considered desirable to satisfy

The above considerations, a different viewpoint, as a separate one restrictions on the thickness h _2, those lower limit of the thickness h _2, or the lower limit of the ratio h _{2 /} h ₁ of the thickness of, and can be said.

As described above, the virtual image display device 100 according to the present embodiment includes the image display device 80 that is a video element that displays an image and the reflection on the first to fifth surfaces S11 to S15 that are a plurality of light guide surfaces. The light guide member 10 that guides the image light GL from the image display device 80 by transmission is provided, and the adjacent incident side light guide surface IG (fourth surface S14) among the first to fifth surfaces S11 to S15. Regarding the exit side light guide surface OG (first surface S11) and the entrance side light guide surface IG and the opposing light guide surface OP (third surface S13) facing the exit side light guide surface OG, the entrance side light guide surface IG. the thickness h ₁ up facing the light guide surface OP is smaller than the thickness h ₂ from the exit side light guide surface OG to the opposite light guide surface OP from.

In the virtual image display device 100, when the light guide member 10 is downsized by utilizing the difference in the thickness provided at the above-mentioned locations among the plurality of light guide surfaces forming the light guide member 10, a wide angle of view is achieved. , It is possible to maintain a more compact shape that fits the observer's head shape.

[Example 1]
Hereinafter, a specific example (Example 1) of the virtual image display device according to the present embodiment will be described with reference to FIG. 9 and the like.

The virtual image display device illustrated in the plan sectional view of FIG. 9 is a more specific aspect of the virtual image display device 100 illustrated in the present embodiment, and FIG. 9 is a diagram corresponding to FIG. 2. Further, FIG. 10 is a graph showing the relationship between the thickness ratio h ₂ /h ₁ of the light guide member 10 and the light guide length L according to the _first embodiment.

Here, as shown in FIG. 9, the light guide length L is viewed from the incident point PI of the light guide member 10 (or the light guide device 20) on the incident side optical axis AX which is the optical axis of the projection optical system 30. It is defined by the distance to the axis OX. Further, the light guide portion length L is set to be about 50 mm. In FIG. 10, the horizontal axis represents the light guide length L, and the vertical axis represents the thickness ratio h ₂ /h ₁ .

In the above, in Example 1, the horizontal angle of view (FOV) is 35° and the refractive index nd is 1.50. Further, in the first embodiment, the light guide member 10 is configured with the value indicated by the point PT1 in FIG. That is, the light guide length L is set to about 50 mm which is a target, and the thickness ratio h ₂ /h ₁ is set to 0.69.

Here, in the above formula (4), k=0.6, m=0.7, the angle θ ₁ of the above formula (5) is adopted instead of the angle α, and the refractive index nd=1. When it is set to 50, the allowable range of the thickness ratio h ₂ /h ₁ is the region DD1 bounded by the straight line R1 in FIG. In this case, the maximum value of h ₂ /h ₁ at L=50 mm is about 0.73. Therefore, in the case of Example 1 in which h ₂ /h ₁ =0.69, this condition, that is, the condition regarding the above equation (4) and the like is satisfied. Further, when h ₂ /h ₁ =0.69, the requirement of the above equation (13) is also satisfied. That is, the thickness ratio h ₂ /h ₁ satisfies both the requirements regarding the upper limit and the lower limit.

As described above, the first embodiment ensures reliable image formation while maintaining a more compact shape that fits the shape of the observer's head when the horizontal angle of view (FOV) is increased to 35°. It is possible.

[Example 2]
Hereinafter, with reference to FIG. 11, a specific example (Example 2) of the virtual image display device according to the present embodiment will be described.

FIG. 11 is a graph showing the relationship between the thickness ratio h ₂ /h ₁ of the light guide member 10 and the light guide portion length L in Example 2, and corresponds to FIG. 10. The configuration of the light guide member 10 is the same as that of the first embodiment illustrated in FIG.

In the above, in the second embodiment, the horizontal field angle (FOV) is 35° and the refractive index nd is 1.55. Further, in the second embodiment, the light guide member 10 is configured with the value indicated by the point PT2 in FIG. That is, the light guide length L is set to a target of about 50 mm, and the thickness ratio h ₂ /h ₁ is set to 0.74.

Here, in the above formula (4), k=0.6, m=0.7, the angle θ ₁ of the above formula (5) is adopted instead of the angle α, and the refractive index nd=1. When it is set to 55, the allowable range of the thickness ratio h ₂ /h ₁ is a region DD2 having the straight line R2 in FIG. 11 as a boundary. In this case, the maximum value of h ₂ /h ₁ at L=50 mm is about 0.9. Therefore, in the case of the second embodiment in which h ₂ /h ₁ =0.74, this condition, that is, the condition regarding the above equation (4) and the like is satisfied. Further, when h ₂ /h ₁ =0.74, the requirement of the above expression (13) is also satisfied. That is, the thickness ratio h ₂ /h ₁ satisfies both the requirements regarding the upper limit and the lower limit.

As described above, the second embodiment secures reliable image formation while maintaining a more compact shape that fits the shape of the observer's head when the horizontal angle of view (FOV) is widened to 35°. It is possible.

[Example 3]
Hereinafter, with reference to FIG. 12, a specific example (Example 3) of the virtual image display device according to the present embodiment will be described.

FIG. 12 is a graph showing the relationship between the thickness ratio h ₂ /h ₁ of the light guide member 10 and the light guide length L in Example 3, and corresponds to FIGS. 10 and 11. The configuration of the light guide member 10 is the same as that of the first embodiment illustrated in FIG.

In the above, in Example 3, the horizontal angle of view (FOV) was set to 45° and the refractive index nd was set to 1.55. Further, in the third embodiment, the light guide member 10 is configured with the value indicated by the point PT3 in FIG. That is, the light guide portion length L is set to 49 mm, which is smaller than the target value of about 50 mm, and the thickness ratio h ₂ /h ₁ is set to the lower limit (minimum) of 0.50.

Here, in the above formula (4), k=0.6, m=0.7, the angle θ ₁ of the above formula (5) is adopted instead of the angle α, and the refractive index nd=1. When it is set to 55, the allowable range of the thickness ratio h ₂ /h ₁ is a region DD3 bounded by the straight line R3 in FIG. In the case of Example 3 in which h ₂ /h ₁ =0.50, this condition, that is, the condition regarding the above equation (4) and the like is satisfied. Further, the requirement of the above equation (13) is also satisfied. That is, the thickness ratio h ₂ /h ₁ satisfies both the requirements regarding the upper limit and the lower limit.

As described above, the first embodiment ensures reliable image formation while maintaining a more compact shape that fits the shape of the observer's head when the horizontal angle of view (FOV) is increased to 45°. It is possible.

[Other]
Although the present invention has been described with reference to the above embodiments, the present invention is not limited to the above embodiments and can be implemented in various modes without departing from the scope of the invention.

First, in the above description, the numerical values such as the horizontal angle of view (FOV) are examples, and can be variously changed according to the required specifications.

In addition to the above, as the image display device 80, in addition to HTPS as a transmissive liquid crystal display device, various other devices can be used. For example, a configuration using a reflective liquid crystal display device is also possible. Therefore, a digital micromirror device or the like can be used instead of the video display element such as a liquid crystal display device.

Further, the generation of ghost light or the like may be further suppressed by providing an AR coat on the lens surface of each lens as appropriate.

In addition to the so-called closed type (not see-through) type virtual image display device for visually recognizing only the image light, the technique of the present invention is adopted in a device that allows an observer to visually recognize or observe the external image, or It may be adapted to a so-called video see-through product including a display and an imaging device.

Further, the technique of the present invention can be applied to a binocular type handheld display and the like.

In addition, in the above, in place of the semi-transmissive reflective film that transmits a part of the image light and reflects the other part, an optical function surface such as a diffractive element such as a volume hologram is provided instead of this. Therefore, it may be possible to play an equivalent role.

As described above, the virtual image display device of one embodiment of the present invention includes a video element for displaying an image and a light guide member for guiding video light from the video element by reflection and transmission on a plurality of light guide surfaces. Of the plurality of light guide surfaces, the incident side light guide surface is provided with respect to the adjacent incident side light guide surface and exit side light guide surface, and the opposing light guide surface facing the incident side light guide surface and the exit side light guide surface. The thickness from the surface to the counter light guide surface is smaller than the thickness from the exit side light guide surface to the counter light guide surface.

In the above virtual image display device, by utilizing the difference in the thickness provided at the above-mentioned locations among the plurality of light guide surfaces forming the light guide member, the light guide member can be miniaturized, thereby increasing the angle of view of the HMD. A more compact shape that fits the observer's head shape can be maintained.

In a specific aspect of the present invention, the light guide member has a step portion that causes a difference in thickness between the incident light guide surface and the exit light guide surface up to the opposing light guide surface. In this case, the step difference can provide a desired difference in thickness.

In another aspect of the present invention, the step portion causes a difference of 2.5 mm or more in the thickness direction between the incident side light guide surface and the exit side light guide surface. In this case, a sufficient difference in thickness can be generated for size reduction.

In still another aspect of the present invention, the step portion has a taper angle of 3° to 10° to connect the incident side light guide surface and the exit side light guide surface. In this case, by providing the taper angle, it is possible to suppress unintended reflection of light at the step portion.

In yet another aspect of the present invention, when the thickness from the exit side light guide surface to the counter light guide surface is h ₁ and the thickness from the incident side light guide surface to the counter light guide surface is h ₂ , For the ratio h ₂ /h ₁ ,
h ₂ /h ₁ ≧0.5
Meet In this case, the optical path of the image light can be secured in the light guide member in consideration of the angle of view.

According to still another aspect of the present invention, it is an intersection of principal rays of components emitted from one end and the other end of the image element which are the most peripheral of the image element and is adjacent to the incident side light guide surface and the emission side light guide surface. At the intersection closest to the location, the value of the thickness from the incident side light guide surface to the opposite light guide surface is larger than the value of the distance from the intersection to the opposite light guide surface. In this case, the optical path of the image light in the light guide member can be secured with reference to the intersection.

In still another aspect of the present invention, the light guide member includes, as a plurality of light guide surfaces, a non-axisymmetric curved surface and forms an intermediate image therein. In this case, a high quality image can be formed while maintaining the optical path length suitable for the HMD.

In still another aspect of the present invention, the incident side light guide surface is formed on a free curved surface portion of the light guide member, and the exit side light guide surface and the counter light guide surface are formed on a flat surface portion of the light guide member. It In this case, it is possible to correct aberrations in the free curved surface portion and maintain good image formation, while ensuring see-through in the flat surface portion.

In still another aspect of the present invention, the light guide member has a first surface, a second surface, a third surface and a fourth surface as a plurality of light guide surfaces, and the fourth surface is an incident side light guide surface. And the third surface is an opposing light guide surface, the first surface is an exit side light guide surface, and the image light is reflected on the fourth surface, reflected on the third surface, and on the first surface. After being reflected and reflected by the second surface, it passes through the first surface and reaches the observation side. In this case, the exit side light guide surface, the counter light guide surface, and the incident side light guide surface can be formed by the first surface, the third surface, and the fourth surface as the plurality of light guide surfaces.

In still another aspect of the present invention, image display with a horizontal angle of view of 25° or more is performed. In this case, it is possible to form an image with a wider angle of view than in the conventional case.

In still another aspect of the present invention, in the light guide member, the distance from the reference incident position of the image light to the reference emission position is 54 mm or less. In this case, the size suitable for the light guide member 10 can be maintained.

In still another aspect of the present invention, the light guide member guides the image light along the direction in which the eyes of the observer are aligned when worn. In this case, it is possible to prevent the design from being largely protruded in the lateral direction.

In still another aspect of the present invention, the light guide member allows the image light and the external light to be visually recognized at the same time by passing through the exit side light guide surface and the opposing light guide surface. In this case, the see-through image formation in which the image light and the external light are superposed and observed makes it possible for the observer to visually recognize in augmented reality (AR).

A virtual image display device of another aspect of the present invention includes a video element that displays an image, and a light guide member that guides video light from the video element by reflection and transmission on a plurality of light guide surfaces. Of the plurality of light guide surfaces, the light guide surface on the exit side and the light guide surface on the exit side, which are arranged on the opposite side to the incident side of the external light and are adjacent to each other, have the light guide surface on the exit side more than the light guide surface on the incident side. It is overhanging.

10... Light guide member, 20... Light guide device, 25... Horizontal angle of view, 30... Projection optical system, 50... Light transmission member, 80... Image display device, 100... Virtual image display device, 102... Frame part, 102a... Center Part, 102b... Support, 104... Temple, 105d... Exterior member, A1 to A3, B1 to B3, C1 to C3... Curve, AR... As appropriate, AX... Optical axis, AX... Incident side optical axis, CC... Central part , CS... Intersection, CT... Center point, D... Eye relief, DD1-DD3... Region, EY... Position, GL... Image light, GLc, GLp... Component light, IG... Incident side light guide surface, IP... Image plane, L... Light guide length, LS... Projection lens, LS1 to LS4... Lens, Lc... Distance, OG... Ejection side light guide surface, OP... Opposing light guide surface, OX... Visual axis, PI... Incident point, PP... Peripheral part , PP1, QQ1... Component, PRc, PRp... Component, PT1-PT3... Point, R1-R3... Straight line, S11-S15... Surface, SP... Step difference portion, SS... Connection surface, d... Step difference, h1... Thickness, h2 ... Thickness, h2/h1... Ratio, hc, hk, hm..., hp, hQ... Distance, i... Eyring diameter, nd... Refractive index, α, α1, α2... Reflection angle, θ1... Angle

Claims (14)

A video element that displays an image,
A light guide member for guiding image light from the image element by reflection and transmission on a plurality of light guide surfaces,
Of the plurality of light guide surfaces, the incident side light guide surface and the exit side light guide surface, and the opposing light guide surface facing the incident side light guide surface and the exit side light guide surface, the incident side A virtual image display device in which the thickness from the light guide surface to the counter light guide surface is smaller than the thickness from the exit side light guide surface to the counter light guide surface. The virtual image according to claim 1, wherein the light guide member has a step portion that causes a difference in thickness up to the opposing light guide surface between the incident light guide surface and the exit light guide surface. Display device. The virtual image display device according to claim 2, wherein the step portion causes a difference of 2.5 mm or more in the thickness direction between the incident-side light guide surface and the exit-side light guide surface. The virtual image display device according to claim 2, wherein the step portion has a taper angle of 3° to 10° to connect the incident side light guide surface and the exit side light guide surface. .. When the thickness from the exit side light guide surface to the counter light guide surface is h ₁ and the thickness from the incident side light guide surface to the counter light guide surface is h ₂ , the thickness ratio h ₂ /h About ₁
h ₂ /h ₁ ≧0.5
The virtual image display device according to any one of claims 1 to 4, which satisfies the above condition. An intersection of chief rays of components emitted from one end and the other end of the image light, which are closest to the periphery of the image element, and which is the closest intersection to the incident side light guide surface and the emission side light guide surface. Regarding the above, the value of the thickness from the incident side light guide surface to the opposite light guide surface is larger than the value of the distance from the intersection to the counter light guide surface, according to any one of claims 1 to 5. The virtual image display device described. The virtual image display device according to claim 1, wherein the light guide member includes non-axisymmetric curved surfaces as the plurality of light guide surfaces, and forms an intermediate image therein. The incident side light guide surface is formed on a free curved surface portion of the light guide member,
The virtual image display device according to claim 1, wherein the exit side light guide surface and the counter light guide surface are formed on a flat surface portion of the light guide member. In the light guide member, the plurality of light guide surfaces include a first surface, a second surface, a third surface, and a fourth surface,
The fourth surface is the incident-side light guide surface,
The third surface is the opposed light guide surface,
The first surface is the exit-side light guide surface,
The image light is reflected by the fourth surface, reflected by the third surface, reflected by the first surface, reflected by the second surface, and then transmitted through the first surface to be observed. The virtual image display device according to any one of claims 1 to 8, which arrives at. The virtual image display device according to claim 1, which displays an image with a horizontal angle of view of 25° or more. The virtual image display device according to claim 1, wherein a distance from a reference incident position of the image light to a reference emission position of the light guide member is 54 mm or less. The virtual image display device according to any one of claims 1 to 11, wherein the light guide member guides the image light along a direction in which an observer's eyes are lined up when worn. 13. The virtual image display device according to claim 1, wherein the light guide member allows the image light and the external light to be visually recognized at the same time by passing through the exit side light guide surface and the counter light guide surface. .. A video element that displays an image,
A light guide member for guiding image light from the image element by reflection and transmission on a plurality of light guide surfaces,
Among the plurality of light guide surfaces, in the incident light guide surface and the exit light guide surface which are arranged on the opposite side to the incident side of the external light and are adjacent to each other, the exit light guide surface is the incident light guide surface. A virtual image display device that is more prominent.

Images